Integrate links to the catalog from the front page

Change some of the text on the front page to link to the new entity catalog page (interim step to getting the catalog page fully integrated into the menu structure)
Adds a glossary page with some basic definitions
Minor tweaks to learnmore page. Improves layout on smaller devices.
We are not grocers.
Merge and close #8 (passive consensus)
Merge and close #9
brooklyn-55 issue
Merge #11
Amendments to PR #11
Merge and close PR #11 with amendments

Conflicts:
	documentation.md